Interactive Systems.   Now there’s a name I’ve not heard in many a year.  Heinz Lycklama went there.

The did a couple of things, a straight UNIX port to various things (PDP-11, 386) and also there “UNIX running under VMS” product.

They also had their own version of the Rand Editor called “INed” that was happiest on this hacked version of a Perkin Elmer terminal.

Early versions were PWB UNIX based if I recall.

My first job out of college was working with IS Unix on an 11/70 playing configuration management (essentially all the PWB stuff).   I also hacked the line printer spooler and the .mm macro package to do classification markings (this was a part of a government contract).

A few years later I was given the job of porting Interactive Systems UNIX that was already running on an i386 (an Intel 310 system which had a Multibus I) to an Intel Multibus II box.    Intel had already ported it once, but nobody seemed to be able to find the source code.    So with a fresh set of the source code for the old system from IS, I proceeded to reverse engineer/port the code to the Message Passing Coprocessor.   (Intel was not real forthcoming for documentation for that either).   Eventually, I got it to work (the Multibus II really was a pleasant bus and worked well with UNIX).   I went on to write drivers for a 9-track tape drive (which sat in my living room for a long time), a Matrox multibus II framebuffer (OK, that had problems), and a SCSI host adapter that was talking to this kludge device that captured digital data from a FLIR on uMatic cassettes (but that’s a different story).